Regenerative pumps have found favor in a number of environments where moderate flow rates at relatively high pressures are desired. A typical regenerative pump is capable of delivering fluid at a head two or three times greater than that of a conventional, single stage centrifugal pump. Because of this, where simplicity is desired, resort has been to regenerative pumps to avoid having to utilize multiple stage pumping systems to achieve the desired pressures.
Unfortunately, regenerative pumps heretofore known have had rather poor suction characteristics, particularly when operating upon a liquid near its boiling point. As the pump attempts to draw liquid into the pumping mechanism, the inlet pressure at the pump is reduced and the overall pressure rise and associated volumetric flow delivery of the pump falls off sharply as a consequence of cavitation. And, of course, as the temperature of the liquid being pumped approaches its boiling point, even a small reduction of pressure at the inlet increases the flash off of liquid to vapor, further complicating the cavitation problem.
The present invention is directed to overcoming one or more of the above difficulties.